My panic alarm goes off while just sitting in my driveway, and when I hit the lock button on my alarm I have always gotten 1 beep, but, off and on I am getting 2 beeps. Any suggestions my Ford dealer can't find anything wrong so they say.

 

You've posted in the general section and not provided any information as to year of truck you have. That would help a great deal.

The horn going off COULD be the panic button being accidently hit. Or, it could be the motion sensor (if so equipped) going off.

1 beep is correct when locking. 2 beeps indicates that it thinks a door or the hood is open. Many times this is the hood switch needing to be reseated, many posts on it.

I suspect that is the cause of both of your issues.